Herpes zoster is a serious and very common disease of aging individuals. The frequency and morbidity of this illnes increases with the age of the patient. Considerable evidence suggests that this correlation reflects a decrease in immunity to varicella zoster virus (VZV)--the causative agent of herpes zoster--as part of the aging process. This project will determine which specific components, or defects in these components, of the immune responses of elderly individuals best correlate with their susceptibility to herpes zoster. This information will complement similar data derived in Project 1 which seeks to correlate immune deficits with post- herpetic pain. Correcting these defects will be the endpoint of a pilot trial in which elderly individuals will receive a live attenuated varicella vaccine. Finally, if an appropriate response to the vaccine is achieved, we will undertake a much larger trial with the goal of enhancing immune responses to VZV sufficiently to prevent herpes zoster.